A metal instrument with a spring to open and close the rubber covered arms, which are inserted into the horse's mouth. The two distance between the two arms can be adjusted.
Context
Made by Arnold and Sons, London and in the 1874 catalogue the listing states a ' Balling Iron, Improved with Regulating Screw, (Professor Varnell's), coverd with India Rubber to protect the gums, very superior £1 1s 0d'.